Atomic and Nuclear Phenomena 

The history of nuclear energy is one that intertwines scientific discovery, technological ingenuity, geopolitical dynamics, and the controversial quest for a powerful energy source. Nuclear materials are part of the earth's crust and have been for millions of years, yet the ability to safely harness nuclear energy for modern power generation is more recent than one might think. Beginning with early 20th-century breakthroughs in atom structure and continuing to present-day debates surrounding its implementation, nuclear energy has been a subject of the world's fascination for over a century.

The roots of nuclear energy can be traced back to the late 19th and early 20th centuries when pioneering physicists began unraveling the mysteries of atomic structure. By revealing that atoms could be split to release immense amounts of energy, the groundbreaking work of figures such as Marie Curie, Ernest Rutherford, and Niels Bohr helped lay the foundation for nuclear power. However, it wasn't until 1939 that nuclear fission, the process of splitting atoms to release energy, was experimentally demonstrated. 

The first controlled nuclear chain reaction occurred in Chicago during the wartime Manhattan Project 1942, a top-secret research and development endeavor that led to the creation of atomic weapons. Three years later, the first nuclear weapon was tested in New Mexico, and in 1948, atomic reactors were the first to generate electricity at a power plant in Idaho. While advancements in this time proved to bring significant technological breakthroughs, concerns surrounding the ethics of using atomic energy were also raised. Consequently, following the war, the focus shifted towards harnessing nuclear energy for peaceful purposes. 

Nuclear energy promised a way to meet the increasing demands for electricity without relying on fossil fuels, reducing greenhouse gas emissions and mitigating environmental impacts.

Throughout the latter half of the 20th century, atomic energy experienced both periods of rapid expansion and periods of stagnation. In the 1950s and 1960s, the world witnessed the birth of the first commercial nuclear power plants, marking a new era for clean and abundant energy. 

The potential for nuclear energy to revolutionize the global energy landscape was met with enthusiasm, leading to the construction of nuclear power plants across the globe. However, catastrophic incidents such as the Chernobyl disaster in 1986 and the Fukushima disaster 2011 raised concerns about nuclear safety and led to public apprehension regarding its implementation.

However, despite the controversies, nuclear energy remains a crucial component of the energy mix in many countries, providing significant electricity generation and contributing to energy security. Developing advanced reactor designs, including thorium-based and small modular reactors, promises a safer and more sustainable nuclear future.

Currently, the most common fuel for nuclear reactors worldwide is uranium-235 (235U), an isotope of uranium. Other fuels, such as thorium, can also be used, but uranium has become the conventional source of most production for various historical, geopolitical, and technical reasons. The critical physical aspect of controlled fission is the chain reaction that begins when a neutron splits a uranium atom. Splitting the atom emits more neutrons, which then split other atoms. During fission, some mass is lost, converted into thermal energy, as described by E=mc2. That heat can be used to make steam to spin a turbine and generate electricity.